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Subject: Re: [PATCH] Documentation: Better document the hardlockup_panic sysctl
From: Christoph von Recklinghausen <crecklin@redhat.com>
In-Reply-To: <20171210074846.20180-1-swood@redhat.com>
Date: Sun, 10 Dec 2017 06:35:18 -0500 (EST)
Cc: Jonathan Corbet <corbet@lwn.net>, linux-kernel@vger.kernel.org,
        Don Zickus <dzickus@redhat.com>
Message-Id: <ADC349E0-B477-4CF7-9661-F036CBD8EF6B@redhat.com>
References: <20171210074846.20180-1-swood@redhat.com>
To: Scott Wood <swood@redhat.com>
Thread-Topic: Documentation: Better document the hardlockup_panic sysctl
Thread-Index: LO3wedNg1MHZsRAmO+drUiyKWlQBAg==
Sender: linux-kernel-owner@vger.kernel.org
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Ack

Sent from my iPhone

> On Dec 10, 2017, at 2:48 AM, Scott Wood <swood@redhat.com> wrote:
> 
> Commit ac1f591249d95372f ("kernel/watchdog.c: add sysctl knob
> hardlockup_panic") added the hardlockup_panic sysctl, but did not add it
> to Documentation/sysctl/kernel.txt.  Add this, and reference it from the
> corresponding entry in Documentation/admin-guide/kernel-parameters.txt.
> 
> Signed-off-by: Scott Wood <swood@redhat.com>
> ---
> Documentation/admin-guide/kernel-parameters.txt |  3 +++
> Documentation/sysctl/kernel.txt                 | 14 ++++++++++++++
> 2 files changed, 17 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 6571fbfdb2a1..dfb7c35b5826 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2538,6 +2538,9 @@
>            This is useful when you use a panic=... timeout and
>            need the box quickly up again.
> 
> +            These settings can be accessed at runtime via
> +            the nmi_watchdog and hardlockup_panic sysctls.
> +
>    netpoll.carrier_timeout=
>            [NET] Specifies amount of time (in seconds) that
>            netpoll should wait for a carrier. By default netpoll
> diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
> index 694968c7523c..63663039acb7 100644
> --- a/Documentation/sysctl/kernel.txt
> +++ b/Documentation/sysctl/kernel.txt
> @@ -34,6 +34,7 @@ show up in /proc/sys/kernel:
> - hostname
> - hotplug
> - hardlockup_all_cpu_backtrace
> +- hardlockup_panic
> - hung_task_panic
> - hung_task_check_count
> - hung_task_timeout_secs
> @@ -313,6 +314,19 @@ will be initiated.
> 1: on detection capture more debug information.
> ==============================================================
> 
> +hardlockup_panic:
> +
> +This parameter can be used to control whether the kernel panics
> +when a hard lockup is detected.
> +
> +   0 - don't panic on hard lockup
> +   1 - panic on hard lockup
> +
> +See Documentation/lockup-watchdogs.txt for more information.  This can
> +also be set using the nmi_watchdog kernel parameter.
> +
> +==============================================================
> +
> hotplug:
> 
> Path for the hotplug policy agent.
> -- 
> 2.9.5
>